פירוש על טהרות 2:7

ר' אליעזר אומר שלשתן שוין – as he explains further on, for Rabbi Eliezer does not hold the purity of heave-offering which is Levitical uncleanness next to Holy Things.

Introduction In today's mishnah Rabbi Eliezer presents his version of exactly how defilement works. The disagreement between Rabbi Eliezer and the other sages is brought at the end of this mishnah.

השלישי שבכולן – third-degree of [ritual defilement] is not found with unconsecrated foods unless they were made through the purity of heave-offering. But the Halakha is not according to Rabbi Eliezer.

Rabbi Eliezer says: the three of them are equivalent.
The first degree of uncleanness in holy food, in terumah or in common food: conveys uncleanness at two removes and causes invalidity at one additional remove in the case of holy food; conveys uncleanness at one remove and causes invalidity at one additional remove in the case of terumah; and causes invalidity in common food. Food that has first degree impurity, no matter what it is (hullin, terumah or holy food), conveys impurity in the same way. This will now be explained. If any food with first degree impurity comes into contact with holy food it conveys uncleanness in two removes. What this means is that if it touches something it gives it second degree impurity and the second degree food conveys third degree. The third degree only invalidates the holy food this food will not convey any other impurity down the line. In the case of terumah it conveys second degree impurity and the second degree invalidates the terumah that it touches. And if it touches common food it invalidates it (in reality it gives it second degree impurity) but such food will not convey any impurity onward.

The second [degree of uncleanness] in the case of all of them: conveys uncleanness at one remove and causes invalidity at one additional remove in the case of holy food; it conveys uncleanness to common liquids and causes invalidity of terumah food. Food that has second degree impurity cause holy food to have third degree impurity and this holy food will invalidate other holy food that it touches. It will defile common liquids, giving them first degree impurity. Note that it will not defile common food, just liquid. And it will invalidate terumah food.

The third degree of uncleanness in the case of all them: conveys uncleanness to holy liquids and causes invalidity to holy food. Something that has third degree impurity will not defile anything common or terumah. But it will cause holy liquids, such as sanctified wine or oil, to have first degree impurity and it will invalidate holy food. This is where Rabbi Eliezer disagrees with the other sages. He holds that terumah that has third degree impurity does not convey uncleanness at two removes and invalidity at one extra remove, as does the opinion in mishnah six. Furthermore, he holds that even common food that has third degree impurity can defile holy food, whereas the previous opinion said it needed to have second degree impurity to do so.